From 448a480aa8d592378732b1052c645b5c681fa7e3 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Tue, 12 Jul 2016 08:37:52 -0700
Subject: [PATCH 1/7] Don't allow `.ts` to appear in an import

---
 src/compiler/program.ts                       | 61 +++++++++++--------
 src/harness/unittests/moduleResolution.ts     |  8 +--
 .../missingFunctionImplementation2.errors.txt |  2 +-
 .../missingFunctionImplementation2.js         |  2 +-
 .../reference/moduleResolutionNoTs.errors.txt | 11 ++++
 .../reference/moduleResolutionNoTs.js         | 15 +++++
 .../moduleResolutionWithExtensions.js         |  7 ---
 .../moduleResolutionWithExtensions.symbols    |  5 --
 .../moduleResolutionWithExtensions.trace.json |  6 --
 .../moduleResolutionWithExtensions.types      |  5 --
 .../staticInstanceResolution5.errors.txt      |  2 +-
 .../reference/staticInstanceResolution5.js    |  2 +-
 .../missingFunctionImplementation2.ts         |  2 +-
 tests/cases/compiler/moduleResolutionNoTs.ts  |  5 ++
 .../compiler/staticInstanceResolution5.ts     |  2 +-
 .../moduleResolutionWithExtensions.ts         |  4 --
 16 files changed, 77 insertions(+), 62 deletions(-)
 create mode 100644 tests/baselines/reference/moduleResolutionNoTs.errors.txt
 create mode 100644 tests/baselines/reference/moduleResolutionNoTs.js
 create mode 100644 tests/cases/compiler/moduleResolutionNoTs.ts

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 988714be2ab1b..5ddf5f7d065c5 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -668,24 +668,37 @@ namespace ts {
      * @param {boolean} onlyRecordFailures - if true then function won't try to actually load files but instead record all attempts as failures. This flag is necessary
      * in cases when we know upfront that all load attempts will fail (because containing folder does not exists) however we still need to record all failed lookup locations.
      */
-    function loadModuleFromFile(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string {
-        // First try to keep/add an extension: importing "./foo.ts" can be matched by a file "./foo.ts", and "./foo" by "./foo.d.ts"
-        const resolvedByAddingOrKeepingExtension = loadModuleFromFileWorker(candidate, extensions, failedLookupLocation, onlyRecordFailures, state);
-        if (resolvedByAddingOrKeepingExtension) {
-            return resolvedByAddingOrKeepingExtension;
+    function loadModuleFromFile(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string | undefined {
+        // If the candidate already has an extension load that or quit.
+        if (hasTypeScriptFileExtension(candidate)) {
+            // Don't allow `.ts` to appear at the end
+            if (!fileExtensionIs(candidate, ".d.ts")) {
+                return undefined;
+            }
+            return tryFile(candidate, failedLookupLocation, onlyRecordFailures, state);
         }
-        // Then try stripping a ".js" or ".jsx" extension and replacing it with a TypeScript one, e.g. "./foo.js" can be matched by "./foo.ts" or "./foo.d.ts"
+
+        // Next, try adding an extension.
+        // We don't allow an import of "foo.ts" to be matched by "foo.ts.ts", but we do allow "foo.js" to be matched by "foo.js.ts".
+        const resolvedByAddingExtension = tryAddingExtensions(candidate, extensions, failedLookupLocation, onlyRecordFailures, state);
+        if (resolvedByAddingExtension) {
+            return resolvedByAddingExtension;
+        }
+
+        // If that didn't work, try stripping a ".js" or ".jsx" extension and replacing it with a TypeScript one;
+        // e.g. "./foo.js" can be matched by "./foo.ts" or "./foo.d.ts"
         if (hasJavaScriptFileExtension(candidate)) {
             const extensionless = removeFileExtension(candidate);
             if (state.traceEnabled) {
                 const extension = candidate.substring(extensionless.length);
                 trace(state.host, Diagnostics.File_name_0_has_a_1_extension_stripping_it, candidate, extension);
             }
-            return loadModuleFromFileWorker(extensionless, extensions, failedLookupLocation, onlyRecordFailures, state);
+            return tryAddingExtensions(extensionless, extensions, failedLookupLocation, onlyRecordFailures, state);
         }
     }
 
-    function loadModuleFromFileWorker(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string {
+    /** Try to return an existing file that adds one of the `extensions` to `candidate`. */
+    function tryAddingExtensions(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string | undefined {
         if (!onlyRecordFailures) {
             // check if containing folder exists - if it doesn't then just record failures for all supported extensions without disk probing
             const directory = getDirectoryPath(candidate);
@@ -693,26 +706,24 @@ namespace ts {
                 onlyRecordFailures = !directoryProbablyExists(directory, state.host);
             }
         }
-        return forEach(extensions, tryLoad);
+        return forEach(extensions, ext =>
+            !(state.skipTsx && isJsxOrTsxExtension(ext)) && tryFile(candidate + ext, failedLookupLocation, onlyRecordFailures, state));
+    }
 
-        function tryLoad(ext: string): string {
-            if (state.skipTsx && isJsxOrTsxExtension(ext)) {
-                return undefined;
-            }
-            const fileName = fileExtensionIs(candidate, ext) ? candidate : candidate + ext;
-            if (!onlyRecordFailures && state.host.fileExists(fileName)) {
-                if (state.traceEnabled) {
-                    trace(state.host, Diagnostics.File_0_exist_use_it_as_a_name_resolution_result, fileName);
-                }
-                return fileName;
+    /** Return the file if it exists. */
+    function tryFile(fileName: string, failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string | undefined {
+        if (!onlyRecordFailures && state.host.fileExists(fileName)) {
+            if (state.traceEnabled) {
+                trace(state.host, Diagnostics.File_0_exist_use_it_as_a_name_resolution_result, fileName);
             }
-            else {
-                if (state.traceEnabled) {
-                    trace(state.host, Diagnostics.File_0_does_not_exist, fileName);
-                }
-                failedLookupLocation.push(fileName);
-                return undefined;
+            return fileName;
+        }
+        else {
+            if (state.traceEnabled) {
+                trace(state.host, Diagnostics.File_0_does_not_exist, fileName);
             }
+            failedLookupLocation.push(fileName);
+            return undefined;
         }
     }
 
diff --git a/src/harness/unittests/moduleResolution.ts b/src/harness/unittests/moduleResolution.ts
index b3f2102d903de..0c312f4701a66 100644
--- a/src/harness/unittests/moduleResolution.ts
+++ b/src/harness/unittests/moduleResolution.ts
@@ -465,8 +465,8 @@ export = C;
                 "/a/B/c/moduleB.ts": `import a = require("./moduleC")`,
                 "/a/B/c/moduleC.ts": "export var x",
                 "/a/B/c/moduleD.ts": `
-import a = require("./moduleA.ts");
-import b = require("./moduleB.ts");
+import a = require("./moduleA");
+import b = require("./moduleB");
                 `
             };
             test(files, { module: ts.ModuleKind.CommonJS, forceConsistentCasingInFileNames: true },  "/a/B/c", /*useCaseSensitiveFileNames*/ false, ["moduleD.ts"], [1149]);
@@ -477,8 +477,8 @@ import b = require("./moduleB.ts");
                 "/a/B/c/moduleB.ts": `import a = require("./moduleC")`,
                 "/a/B/c/moduleC.ts": "export var x",
                 "/a/B/c/moduleD.ts": `
-import a = require("./moduleA.ts");
-import b = require("./moduleB.ts");
+import a = require("./moduleA");
+import b = require("./moduleB");
                 `
             };
             test(files, { module: ts.ModuleKind.CommonJS, forceConsistentCasingInFileNames: true },  "/a/B/c", /*useCaseSensitiveFileNames*/ false, ["moduleD.ts"], []);
diff --git a/tests/baselines/reference/missingFunctionImplementation2.errors.txt b/tests/baselines/reference/missingFunctionImplementation2.errors.txt
index a695482e1fba3..86d8baba6f780 100644
--- a/tests/baselines/reference/missingFunctionImplementation2.errors.txt
+++ b/tests/baselines/reference/missingFunctionImplementation2.errors.txt
@@ -4,7 +4,7 @@ tests/cases/compiler/missingFunctionImplementation2_b.ts(1,17): error TS2391: Fu
 
 ==== tests/cases/compiler/missingFunctionImplementation2_a.ts (1 errors) ====
     export {};
-    declare module "./missingFunctionImplementation2_b.ts" {
+    declare module "./missingFunctionImplementation2_b" {
       export function f(a, b): void;
                       ~
 !!! error TS2384: Overload signatures must all be ambient or non-ambient.
diff --git a/tests/baselines/reference/missingFunctionImplementation2.js b/tests/baselines/reference/missingFunctionImplementation2.js
index 104b6dd9443d6..7b3456015c832 100644
--- a/tests/baselines/reference/missingFunctionImplementation2.js
+++ b/tests/baselines/reference/missingFunctionImplementation2.js
@@ -2,7 +2,7 @@
 
 //// [missingFunctionImplementation2_a.ts]
 export {};
-declare module "./missingFunctionImplementation2_b.ts" {
+declare module "./missingFunctionImplementation2_b" {
   export function f(a, b): void;
 }
 
diff --git a/tests/baselines/reference/moduleResolutionNoTs.errors.txt b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
new file mode 100644
index 0000000000000..d1d6270ae136f
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/user.ts(1,15): error TS2307: Cannot find module './m.ts'.
+
+
+==== tests/cases/compiler/m.ts (0 errors) ====
+    export default 0;
+    
+==== tests/cases/compiler/user.ts (1 errors) ====
+    import x from "./m.ts";
+                  ~~~~~~~~
+!!! error TS2307: Cannot find module './m.ts'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionNoTs.js b/tests/baselines/reference/moduleResolutionNoTs.js
new file mode 100644
index 0000000000000..2a56947ce198a
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionNoTs.js
@@ -0,0 +1,15 @@
+//// [tests/cases/compiler/moduleResolutionNoTs.ts] ////
+
+//// [m.ts]
+export default 0;
+
+//// [user.ts]
+import x from "./m.ts";
+
+
+//// [m.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = 0;
+//// [user.js]
+"use strict";
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions.js b/tests/baselines/reference/moduleResolutionWithExtensions.js
index df12a3531bcfa..16d176872cac1 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions.js
+++ b/tests/baselines/reference/moduleResolutionWithExtensions.js
@@ -8,10 +8,6 @@ export default 0;
 //// [b.ts]
 import a from './a';
 
-// Matching extension
-//// [c.ts]
-import a from './a.ts';
-
 // '.js' extension: stripped and replaced with '.ts'
 //// [d.ts]
 import a from './a.js';
@@ -36,9 +32,6 @@ exports["default"] = 0;
 // No extension: '.ts' added 
 //// [b.js]
 "use strict";
-// Matching extension 
-//// [c.js]
-"use strict";
 // '.js' extension: stripped and replaced with '.ts' 
 //// [d.js]
 "use strict";
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions.symbols b/tests/baselines/reference/moduleResolutionWithExtensions.symbols
index e9934946a64fd..eaaa1d51cc097 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions.symbols
+++ b/tests/baselines/reference/moduleResolutionWithExtensions.symbols
@@ -7,11 +7,6 @@ No type information for this code.=== /src/b.ts ===
 import a from './a';
 >a : Symbol(a, Decl(b.ts, 0, 6))
 
-// Matching extension
-=== /src/c.ts ===
-import a from './a.ts';
->a : Symbol(a, Decl(c.ts, 0, 6))
-
 // '.js' extension: stripped and replaced with '.ts'
 === /src/d.ts ===
 import a from './a.js';
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions.trace.json b/tests/baselines/reference/moduleResolutionWithExtensions.trace.json
index 7dc9e8c104b8c..5060006ac56bd 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions.trace.json
+++ b/tests/baselines/reference/moduleResolutionWithExtensions.trace.json
@@ -5,12 +5,6 @@
     "File '/src/a.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/src/a.ts', result '/src/a.ts'",
     "======== Module name './a' was successfully resolved to '/src/a.ts'. ========",
-    "======== Resolving module './a.ts' from '/src/c.ts'. ========",
-    "Module resolution kind is not specified, using 'NodeJs'.",
-    "Loading module as file / folder, candidate module location '/src/a.ts'.",
-    "File '/src/a.ts' exist - use it as a name resolution result.",
-    "Resolving real path for '/src/a.ts', result '/src/a.ts'",
-    "======== Module name './a.ts' was successfully resolved to '/src/a.ts'. ========",
     "======== Resolving module './a.js' from '/src/d.ts'. ========",
     "Module resolution kind is not specified, using 'NodeJs'.",
     "Loading module as file / folder, candidate module location '/src/a.js'.",
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions.types b/tests/baselines/reference/moduleResolutionWithExtensions.types
index fbc0091ee3b95..f59eda1a81e79 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions.types
+++ b/tests/baselines/reference/moduleResolutionWithExtensions.types
@@ -7,11 +7,6 @@ No type information for this code.=== /src/b.ts ===
 import a from './a';
 >a : number
 
-// Matching extension
-=== /src/c.ts ===
-import a from './a.ts';
->a : number
-
 // '.js' extension: stripped and replaced with '.ts'
 === /src/d.ts ===
 import a from './a.js';
diff --git a/tests/baselines/reference/staticInstanceResolution5.errors.txt b/tests/baselines/reference/staticInstanceResolution5.errors.txt
index da6f0fde1433a..f36851b2b97e8 100644
--- a/tests/baselines/reference/staticInstanceResolution5.errors.txt
+++ b/tests/baselines/reference/staticInstanceResolution5.errors.txt
@@ -4,7 +4,7 @@ tests/cases/compiler/staticInstanceResolution5_1.ts(6,16): error TS2304: Cannot
 
 
 ==== tests/cases/compiler/staticInstanceResolution5_1.ts (3 errors) ====
-    import WinJS = require('staticInstanceResolution5_0.ts');
+    import WinJS = require('staticInstanceResolution5_0');
     
     // these 3 should be errors
     var x = (w1: WinJS) => { };
diff --git a/tests/baselines/reference/staticInstanceResolution5.js b/tests/baselines/reference/staticInstanceResolution5.js
index 0809d1af5f059..b3514e00aad87 100644
--- a/tests/baselines/reference/staticInstanceResolution5.js
+++ b/tests/baselines/reference/staticInstanceResolution5.js
@@ -8,7 +8,7 @@ export class Promise {
 }
 
 //// [staticInstanceResolution5_1.ts]
-import WinJS = require('staticInstanceResolution5_0.ts');
+import WinJS = require('staticInstanceResolution5_0');
 
 // these 3 should be errors
 var x = (w1: WinJS) => { };
diff --git a/tests/cases/compiler/missingFunctionImplementation2.ts b/tests/cases/compiler/missingFunctionImplementation2.ts
index 25909b6add4c2..1717bc663f270 100644
--- a/tests/cases/compiler/missingFunctionImplementation2.ts
+++ b/tests/cases/compiler/missingFunctionImplementation2.ts
@@ -1,6 +1,6 @@
 // @Filename: missingFunctionImplementation2_a.ts
 export {};
-declare module "./missingFunctionImplementation2_b.ts" {
+declare module "./missingFunctionImplementation2_b" {
   export function f(a, b): void;
 }
 
diff --git a/tests/cases/compiler/moduleResolutionNoTs.ts b/tests/cases/compiler/moduleResolutionNoTs.ts
new file mode 100644
index 0000000000000..18b042d905fd9
--- /dev/null
+++ b/tests/cases/compiler/moduleResolutionNoTs.ts
@@ -0,0 +1,5 @@
+// @filename: m.ts
+export default 0;
+
+// @filename: user.ts
+import x from "./m.ts";
diff --git a/tests/cases/compiler/staticInstanceResolution5.ts b/tests/cases/compiler/staticInstanceResolution5.ts
index 3adb8667be578..ed34dbd535f27 100644
--- a/tests/cases/compiler/staticInstanceResolution5.ts
+++ b/tests/cases/compiler/staticInstanceResolution5.ts
@@ -7,7 +7,7 @@ export class Promise {
 }
 
 // @Filename: staticInstanceResolution5_1.ts
-import WinJS = require('staticInstanceResolution5_0.ts');
+import WinJS = require('staticInstanceResolution5_0');
 
 // these 3 should be errors
 var x = (w1: WinJS) => { };
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithExtensions.ts b/tests/cases/conformance/externalModules/moduleResolutionWithExtensions.ts
index 6ad3565862337..429289546c5ea 100644
--- a/tests/cases/conformance/externalModules/moduleResolutionWithExtensions.ts
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithExtensions.ts
@@ -7,10 +7,6 @@ export default 0;
 // @Filename: /src/b.ts
 import a from './a';
 
-// Matching extension
-// @Filename: /src/c.ts
-import a from './a.ts';
-
 // '.js' extension: stripped and replaced with '.ts'
 // @Filename: /src/d.ts
 import a from './a.js';

From a8c05a98e98b0e2f7d50d983ac08d385d6dd3641 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Tue, 12 Jul 2016 11:11:03 -0700
Subject: [PATCH 2/7] Add specific error message for unwanted '.ts' extension

---
 src/compiler/checker.ts                             |  7 ++++++-
 src/compiler/core.ts                                |  3 ++-
 src/compiler/diagnosticMessages.json                |  4 ++++
 src/compiler/utilities.ts                           |  4 ++++
 .../reference/moduleResolutionNoTs.errors.txt       | 13 ++++++++-----
 tests/baselines/reference/moduleResolutionNoTs.js   |  5 +++++
 tests/cases/compiler/moduleResolutionNoTs.ts        |  3 +++
 7 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 1cebd4693885b..88565bcba92c3 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1342,7 +1342,12 @@ namespace ts {
 
             if (moduleNotFoundError) {
                 // report errors only if it was requested
-                error(moduleReferenceLiteral, moduleNotFoundError, moduleName);
+                if (hasTypeScriptFileExtensionNonDts(moduleName)) {
+                    error(moduleReferenceLiteral, Diagnostics.Module_name_should_not_include_a_ts_extension_Colon_0, moduleName);
+                }
+                else {
+                    error(moduleReferenceLiteral, moduleNotFoundError, moduleName);
+                }
             }
             return undefined;
         }
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 926ee38a79514..9b12f6a7f6861 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1144,7 +1144,8 @@ namespace ts {
     /**
      *  List of supported extensions in order of file resolution precedence.
      */
-    export const supportedTypeScriptExtensions = [".ts", ".tsx", ".d.ts"];
+    export const supportedTypeScriptExtensionsNonDts = [".ts", ".tsx"];
+    export const supportedTypeScriptExtensions = supportedTypeScriptExtensionsNonDts.concat([".d.ts"]);
     export const supportedJavascriptExtensions = [".js", ".jsx"];
     const allSupportedExtensions  = supportedTypeScriptExtensions.concat(supportedJavascriptExtensions);
 
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 8ffb02a89743e..d85dc20afdfdd 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1943,6 +1943,10 @@
         "category": "Error",
         "code": 2689
     },
+    "Module name should not include a '.ts' extension: '{0}'.": {
+        "category": "Error",
+        "code": 2690
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 7219a5bbd24ab..bfe8e4bd657b8 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2726,6 +2726,10 @@ namespace ts {
         return forEach(supportedTypeScriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
 
+    export function hasTypeScriptFileExtensionNonDts(fileName: string) {
+        return forEach(supportedTypeScriptExtensionsNonDts, extension => fileExtensionIs(fileName, extension));
+    }
+
     /**
      * Replace each instance of non-ascii characters by one, two, three, or four escape sequences
      * representing the UTF-8 encoding of the character, and return the expanded char code list.
diff --git a/tests/baselines/reference/moduleResolutionNoTs.errors.txt b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
index d1d6270ae136f..de105f7353965 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.errors.txt
+++ b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
@@ -1,11 +1,14 @@
-tests/cases/compiler/user.ts(1,15): error TS2307: Cannot find module './m.ts'.
+tests/cases/compiler/user.ts(4,15): error TS2690: Module name should not include a '.ts' extension: './m.ts'.
 
 
-==== tests/cases/compiler/m.ts (0 errors) ====
-    export default 0;
-    
 ==== tests/cases/compiler/user.ts (1 errors) ====
+    // '.ts' extension is OK in a reference
+    ///<reference path="./m.ts"/>
+    
     import x from "./m.ts";
                   ~~~~~~~~
-!!! error TS2307: Cannot find module './m.ts'.
+!!! error TS2690: Module name should not include a '.ts' extension: './m.ts'.
+    
+==== tests/cases/compiler/m.ts (0 errors) ====
+    export default 0;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionNoTs.js b/tests/baselines/reference/moduleResolutionNoTs.js
index 2a56947ce198a..8a912f33011f6 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.js
+++ b/tests/baselines/reference/moduleResolutionNoTs.js
@@ -4,6 +4,9 @@
 export default 0;
 
 //// [user.ts]
+// '.ts' extension is OK in a reference
+///<reference path="./m.ts"/>
+
 import x from "./m.ts";
 
 
@@ -12,4 +15,6 @@ import x from "./m.ts";
 exports.__esModule = true;
 exports["default"] = 0;
 //// [user.js]
+// '.ts' extension is OK in a reference
+///<reference path="./m.ts"/>
 "use strict";
diff --git a/tests/cases/compiler/moduleResolutionNoTs.ts b/tests/cases/compiler/moduleResolutionNoTs.ts
index 18b042d905fd9..29d81589cd92c 100644
--- a/tests/cases/compiler/moduleResolutionNoTs.ts
+++ b/tests/cases/compiler/moduleResolutionNoTs.ts
@@ -2,4 +2,7 @@
 export default 0;
 
 // @filename: user.ts
+// '.ts' extension is OK in a reference
+///<reference path="./m.ts"/>
+
 import x from "./m.ts";

From 0f134ed69efb8d59919bcec6a1e702f403665af6 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Tue, 2 Aug 2016 06:58:26 -0700
Subject: [PATCH 3/7] Improve error message

---
 src/compiler/checker.ts                       |  6 +++--
 src/compiler/core.ts                          | 21 ++++++++++++++---
 src/compiler/diagnosticMessages.json          |  2 +-
 src/compiler/utilities.ts                     |  5 ++--
 .../reference/moduleResolutionNoTs.errors.txt | 23 ++++++++++++++-----
 .../reference/moduleResolutionNoTs.js         | 22 ++++++++++++++----
 tests/cases/compiler/moduleResolutionNoTs.ts  | 14 ++++++++---
 7 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 7eab69f1df66c..290fa257daf9b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1366,8 +1366,10 @@ namespace ts {
 
             if (moduleNotFoundError) {
                 // report errors only if it was requested
-                if (hasTypeScriptFileExtensionNonDts(moduleName)) {
-                    error(moduleReferenceLiteral, Diagnostics.Module_name_should_not_include_a_ts_extension_Colon_0, moduleName);
+                const nonDtsExtension = tryExtractTypeScriptExtensionNonDts(moduleName);
+                if (nonDtsExtension) {
+                    const diag = Diagnostics.An_import_path_should_not_end_with_a_0_extension_Consider_importing_1_instead;
+                    error(moduleReferenceLiteral, diag, nonDtsExtension, removeExtension(moduleName, nonDtsExtension));
                 }
                 else {
                     error(moduleReferenceLiteral, moduleNotFoundError, moduleName);
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 7d6aea6246216..d77036660b0a7 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -93,6 +93,17 @@ namespace ts {
         return undefined;
     }
 
+    /** Works like Array.prototype.find. */
+    export function find<T>(array: T[], predicate: (element: T, index: number) => boolean): T | undefined {
+        for (let i = 0, len = array.length; i < len; i++) {
+            const value = array[i];
+            if (predicate(value, i)) {
+                return value;
+            }
+        }
+        return undefined;
+    }
+
     export function contains<T>(array: T[], value: T): boolean {
         if (array) {
             for (const v of array) {
@@ -941,7 +952,7 @@ namespace ts {
      *  [^./]                   # matches everything up to the first . character (excluding directory seperators)
      *  (\\.(?!min\\.js$))?     # matches . characters but not if they are part of the .min.js file extension
      */
-    const singleAsteriskRegexFragmentFiles = "([^./]|(\\.(?!min\\.js$))?)*";
+    const singleAsteriskRegexFragmentFiles = "([^./]|(\\.(?!min\\.js$))?)*";
     const singleAsteriskRegexFragmentOther = "[^/]*";
 
     export function getRegularExpressionForWildcard(specs: string[], basePath: string, usage: "files" | "directories" | "exclude") {
@@ -1271,8 +1282,12 @@ namespace ts {
         return path;
     }
 
-    export function tryRemoveExtension(path: string, extension: string): string {
-        return fileExtensionIs(path, extension) ? path.substring(0, path.length - extension.length) : undefined;
+    export function tryRemoveExtension(path: string, extension: string): string | undefined {
+        return fileExtensionIs(path, extension) ? removeExtension(path, extension) : undefined;
+    }
+
+    export function removeExtension(path: string, extension: string): string {
+        return path.substring(0, path.length - extension.length);
     }
 
     export function isJsxOrTsxExtension(ext: string): boolean {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index ff534847cda44..93bd6c608f002 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1951,7 +1951,7 @@
         "category": "Error",
         "code": 2690
     },
-    "Module name should not include a '.ts' extension: '{0}'.": {
+    "An import path should not end with a '{0}' extension. Consider importing '{1}' instead.": {
         "category": "Error",
         "code": 2691
     },
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index d6667d2b8b20e..b92037b7e5b53 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2726,8 +2726,9 @@ namespace ts {
         return forEach(supportedTypeScriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
 
-    export function hasTypeScriptFileExtensionNonDts(fileName: string) {
-        return forEach(supportedTypeScriptExtensionsNonDts, extension => fileExtensionIs(fileName, extension));
+    /** Return ".ts" or ".tsx" if that is the extension. */
+    export function tryExtractTypeScriptExtensionNonDts(fileName: string): string | undefined {
+        return find(supportedTypeScriptExtensionsNonDts, extension => fileExtensionIs(fileName, extension));
     }
 
     /**
diff --git a/tests/baselines/reference/moduleResolutionNoTs.errors.txt b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
index de105f7353965..2a9b74a1af674 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.errors.txt
+++ b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
@@ -1,14 +1,25 @@
-tests/cases/compiler/user.ts(4,15): error TS2690: Module name should not include a '.ts' extension: './m.ts'.
+tests/cases/compiler/user.ts(4,15): error TS2691: An import path should not end with a '.ts' extension. Consider importing './x' instead.
+tests/cases/compiler/user.ts(5,15): error TS2691: An import path should not end with a '.tsx' extension. Consider importing './y' instead.
 
 
-==== tests/cases/compiler/user.ts (1 errors) ====
+==== tests/cases/compiler/user.ts (2 errors) ====
     // '.ts' extension is OK in a reference
-    ///<reference path="./m.ts"/>
+    ///<reference path="./x.ts"/>
     
-    import x from "./m.ts";
+    import x from "./x.ts";
                   ~~~~~~~~
-!!! error TS2690: Module name should not include a '.ts' extension: './m.ts'.
+!!! error TS2691: An import path should not end with a '.ts' extension. Consider importing './x' instead.
+    import y from "./y.tsx";
+                  ~~~~~~~~~
+!!! error TS2691: An import path should not end with a '.tsx' extension. Consider importing './y' instead.
     
-==== tests/cases/compiler/m.ts (0 errors) ====
+    // Making sure the suggested fixes are valid:
+    import x2 from "./x";
+    import y2 from "./y";
+    
+==== tests/cases/compiler/x.ts (0 errors) ====
+    export default 0;
+    
+==== tests/cases/compiler/y.tsx (0 errors) ====
     export default 0;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionNoTs.js b/tests/baselines/reference/moduleResolutionNoTs.js
index 8a912f33011f6..d9d918f5600df 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.js
+++ b/tests/baselines/reference/moduleResolutionNoTs.js
@@ -1,20 +1,32 @@
 //// [tests/cases/compiler/moduleResolutionNoTs.ts] ////
 
-//// [m.ts]
+//// [x.ts]
+export default 0;
+
+//// [y.tsx]
 export default 0;
 
 //// [user.ts]
 // '.ts' extension is OK in a reference
-///<reference path="./m.ts"/>
+///<reference path="./x.ts"/>
+
+import x from "./x.ts";
+import y from "./y.tsx";
 
-import x from "./m.ts";
+// Making sure the suggested fixes are valid:
+import x2 from "./x";
+import y2 from "./y";
 
 
-//// [m.js]
+//// [x.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = 0;
+//// [y.js]
 "use strict";
 exports.__esModule = true;
 exports["default"] = 0;
 //// [user.js]
 // '.ts' extension is OK in a reference
-///<reference path="./m.ts"/>
+///<reference path="./x.ts"/>
 "use strict";
diff --git a/tests/cases/compiler/moduleResolutionNoTs.ts b/tests/cases/compiler/moduleResolutionNoTs.ts
index 29d81589cd92c..683f6630d9f30 100644
--- a/tests/cases/compiler/moduleResolutionNoTs.ts
+++ b/tests/cases/compiler/moduleResolutionNoTs.ts
@@ -1,8 +1,16 @@
-// @filename: m.ts
+// @filename: x.ts
+export default 0;
+
+// @filename: y.tsx
 export default 0;
 
 // @filename: user.ts
 // '.ts' extension is OK in a reference
-///<reference path="./m.ts"/>
+///<reference path="./x.ts"/>
+
+import x from "./x.ts";
+import y from "./y.tsx";
 
-import x from "./m.ts";
+// Making sure the suggested fixes are valid:
+import x2 from "./x";
+import y2 from "./y";

From 359c8b12ef3a8339940edd9203dcb2a10c08615b Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Wed, 3 Aug 2016 07:12:10 -0700
Subject: [PATCH 4/7] Don't allow ".d.ts" extension in an import either.

---
 src/compiler/checker.ts                       |  8 ++---
 src/compiler/core.ts                          |  3 +-
 src/compiler/diagnosticMessages.json          |  2 +-
 src/compiler/program.ts                       | 16 +++-------
 src/compiler/utilities.ts                     |  6 ++--
 src/harness/compilerRunner.ts                 |  2 +-
 .../reference/moduleResolutionNoTs.errors.txt | 32 +++++++++++--------
 .../reference/moduleResolutionNoTs.js         | 11 ++++---
 tests/cases/compiler/moduleResolutionNoTs.ts  |  9 ++++--
 9 files changed, 46 insertions(+), 43 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 290fa257daf9b..6dd2747e33f96 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1366,10 +1366,10 @@ namespace ts {
 
             if (moduleNotFoundError) {
                 // report errors only if it was requested
-                const nonDtsExtension = tryExtractTypeScriptExtensionNonDts(moduleName);
-                if (nonDtsExtension) {
-                    const diag = Diagnostics.An_import_path_should_not_end_with_a_0_extension_Consider_importing_1_instead;
-                    error(moduleReferenceLiteral, diag, nonDtsExtension, removeExtension(moduleName, nonDtsExtension));
+                const tsExtension = tryExtractTypeScriptExtension(moduleName);
+                if (tsExtension) {
+                    const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
+                    error(moduleReferenceLiteral, diag, tsExtension, removeExtension(moduleName, tsExtension));
                 }
                 else {
                     error(moduleReferenceLiteral, moduleNotFoundError, moduleName);
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index d77036660b0a7..869cddb2d4d0b 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1198,8 +1198,7 @@ namespace ts {
     /**
      *  List of supported extensions in order of file resolution precedence.
      */
-    export const supportedTypeScriptExtensionsNonDts = [".ts", ".tsx"];
-    export const supportedTypeScriptExtensions = supportedTypeScriptExtensionsNonDts.concat([".d.ts"]);
+    export const supportedTypeScriptExtensions = [".ts", ".tsx", ".d.ts"];
     export const supportedJavascriptExtensions = [".js", ".jsx"];
     const allSupportedExtensions  = supportedTypeScriptExtensions.concat(supportedJavascriptExtensions);
 
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 93bd6c608f002..8975e5daa04cf 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1951,7 +1951,7 @@
         "category": "Error",
         "code": 2690
     },
-    "An import path should not end with a '{0}' extension. Consider importing '{1}' instead.": {
+    "An import path cannot end with a '{0}' extension. Consider importing '{1}' instead.": {
         "category": "Error",
         "code": 2691
     },
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index a2674d7978326..d35ce644120c4 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -669,17 +669,7 @@ namespace ts {
      * in cases when we know upfront that all load attempts will fail (because containing folder does not exists) however we still need to record all failed lookup locations.
      */
     function loadModuleFromFile(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string | undefined {
-        // If the candidate already has an extension load that or quit.
-        if (hasTypeScriptFileExtension(candidate)) {
-            // Don't allow `.ts` to appear at the end
-            if (!fileExtensionIs(candidate, ".d.ts")) {
-                return undefined;
-            }
-            return tryFile(candidate, failedLookupLocation, onlyRecordFailures, state);
-        }
-
-        // Next, try adding an extension.
-        // We don't allow an import of "foo.ts" to be matched by "foo.ts.ts", but we do allow "foo.js" to be matched by "foo.js.ts".
+        // First, try adding an extension. An import of "foo" could be matched by a file "foo.ts", or "foo.js" by "foo.js.ts"
         const resolvedByAddingExtension = tryAddingExtensions(candidate, extensions, failedLookupLocation, onlyRecordFailures, state);
         if (resolvedByAddingExtension) {
             return resolvedByAddingExtension;
@@ -736,7 +726,9 @@ namespace ts {
             }
             const typesFile = tryReadTypesSection(packageJsonPath, candidate, state);
             if (typesFile) {
-                const result = loadModuleFromFile(typesFile, extensions, failedLookupLocation, !directoryProbablyExists(getDirectoryPath(typesFile), state.host), state);
+                const onlyRecordFailures = !directoryProbablyExists(getDirectoryPath(typesFile), state.host);
+                // The package.json "typings" property must specify the file with extension, so just try that exact filename.
+                const result = tryFile(typesFile, failedLookupLocation, onlyRecordFailures, state);
                 if (result) {
                     return result;
                 }
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index b92037b7e5b53..22c9355072524 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2727,9 +2727,11 @@ namespace ts {
     }
 
     /** Return ".ts" or ".tsx" if that is the extension. */
-    export function tryExtractTypeScriptExtensionNonDts(fileName: string): string | undefined {
-        return find(supportedTypeScriptExtensionsNonDts, extension => fileExtensionIs(fileName, extension));
+    export function tryExtractTypeScriptExtension(fileName: string): string | undefined {
+        return find(supportedTypescriptExtensionsWithDtsFirst, extension => fileExtensionIs(fileName, extension));
     }
+    // Must have '.d.ts' first because if '.ts' goes first, that will be detected as the extension instead of '.d.ts'.
+    const supportedTypescriptExtensionsWithDtsFirst = supportedTypeScriptExtensions.slice().reverse();
 
     /**
      * Replace each instance of non-ascii characters by one, two, three, or four escape sequences
diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index ecdc18394b079..b8467adda5ce4 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -52,7 +52,7 @@ class CompilerBaselineRunner extends RunnerBase {
     private makeUnitName(name: string, root: string) {
         const path = ts.toPath(name, root, (fileName) => Harness.Compiler.getCanonicalFileName(fileName));
         const pathStart = ts.toPath(Harness.IO.getCurrentDirectory(), "", (fileName) => Harness.Compiler.getCanonicalFileName(fileName));
-        return path.replace(pathStart, "/");
+        return pathStart === "" ? path : path.replace(pathStart, "/");
     };
 
     public checkTestCodeOutput(fileName: string) {
diff --git a/tests/baselines/reference/moduleResolutionNoTs.errors.txt b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
index 2a9b74a1af674..c054330731158 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.errors.txt
+++ b/tests/baselines/reference/moduleResolutionNoTs.errors.txt
@@ -1,25 +1,31 @@
-tests/cases/compiler/user.ts(4,15): error TS2691: An import path should not end with a '.ts' extension. Consider importing './x' instead.
-tests/cases/compiler/user.ts(5,15): error TS2691: An import path should not end with a '.tsx' extension. Consider importing './y' instead.
+tests/cases/compiler/user.ts(1,15): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './x' instead.
+tests/cases/compiler/user.ts(2,15): error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './y' instead.
+tests/cases/compiler/user.ts(3,15): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './z' instead.
 
 
-==== tests/cases/compiler/user.ts (2 errors) ====
-    // '.ts' extension is OK in a reference
-    ///<reference path="./x.ts"/>
+==== tests/cases/compiler/x.ts (0 errors) ====
+    export default 0;
+    
+==== tests/cases/compiler/y.tsx (0 errors) ====
+    export default 0;
+    
+==== tests/cases/compiler/z.d.ts (0 errors) ====
+    declare const x: number;
+    export default x;
     
+==== tests/cases/compiler/user.ts (3 errors) ====
     import x from "./x.ts";
                   ~~~~~~~~
-!!! error TS2691: An import path should not end with a '.ts' extension. Consider importing './x' instead.
+!!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './x' instead.
     import y from "./y.tsx";
                   ~~~~~~~~~
-!!! error TS2691: An import path should not end with a '.tsx' extension. Consider importing './y' instead.
+!!! error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './y' instead.
+    import z from "./z.d.ts";
+                  ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './z' instead.
     
     // Making sure the suggested fixes are valid:
     import x2 from "./x";
     import y2 from "./y";
-    
-==== tests/cases/compiler/x.ts (0 errors) ====
-    export default 0;
-    
-==== tests/cases/compiler/y.tsx (0 errors) ====
-    export default 0;
+    import z2 from "./z";
     
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionNoTs.js b/tests/baselines/reference/moduleResolutionNoTs.js
index d9d918f5600df..9ff33d688ea24 100644
--- a/tests/baselines/reference/moduleResolutionNoTs.js
+++ b/tests/baselines/reference/moduleResolutionNoTs.js
@@ -6,16 +6,19 @@ export default 0;
 //// [y.tsx]
 export default 0;
 
+//// [z.d.ts]
+declare const x: number;
+export default x;
+
 //// [user.ts]
-// '.ts' extension is OK in a reference
-///<reference path="./x.ts"/>
-
 import x from "./x.ts";
 import y from "./y.tsx";
+import z from "./z.d.ts";
 
 // Making sure the suggested fixes are valid:
 import x2 from "./x";
 import y2 from "./y";
+import z2 from "./z";
 
 
 //// [x.js]
@@ -27,6 +30,4 @@ exports["default"] = 0;
 exports.__esModule = true;
 exports["default"] = 0;
 //// [user.js]
-// '.ts' extension is OK in a reference
-///<reference path="./x.ts"/>
 "use strict";
diff --git a/tests/cases/compiler/moduleResolutionNoTs.ts b/tests/cases/compiler/moduleResolutionNoTs.ts
index 683f6630d9f30..2051bc259bf0e 100644
--- a/tests/cases/compiler/moduleResolutionNoTs.ts
+++ b/tests/cases/compiler/moduleResolutionNoTs.ts
@@ -4,13 +4,16 @@ export default 0;
 // @filename: y.tsx
 export default 0;
 
-// @filename: user.ts
-// '.ts' extension is OK in a reference
-///<reference path="./x.ts"/>
+// @filename: z.d.ts
+declare const x: number;
+export default x;
 
+// @filename: user.ts
 import x from "./x.ts";
 import y from "./y.tsx";
+import z from "./z.d.ts";
 
 // Making sure the suggested fixes are valid:
 import x2 from "./x";
 import y2 from "./y";
+import z2 from "./z";

From 2eb159e269f79f1c7d86723b2a0d9c44739627fd Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Mon, 15 Aug 2016 10:34:07 -0700
Subject: [PATCH 5/7] Rename 'find' functions

---
 src/compiler/checker.ts   | 2 +-
 src/compiler/core.ts      | 9 ++++++---
 src/compiler/utilities.ts | 2 +-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 583ae5a1f3528..37f13dbf807fe 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1032,7 +1032,7 @@ namespace ts {
         }
 
         function getDeclarationOfAliasSymbol(symbol: Symbol): Declaration {
-            return find(symbol.declarations, d => isAliasSymbolDeclaration(d) ? d : undefined);
+            return findMap(symbol.declarations, d => isAliasSymbolDeclaration(d) ? d : undefined);
         }
 
         function getTargetOfImportEqualsDeclaration(node: ImportEqualsDeclaration): Symbol {
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 36db85061b00b..d2ea69b304dd7 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -110,7 +110,7 @@ namespace ts {
     }
 
     /** Works like Array.prototype.find, returning `undefined` if no element satisfying the predicate is found. */
-    export function tryFind<T>(array: T[], predicate: (element: T, index: number) => boolean): T | undefined {
+    export function find<T>(array: T[], predicate: (element: T, index: number) => boolean): T | undefined {
         for (let i = 0, len = array.length; i < len; i++) {
             const value = array[i];
             if (predicate(value, i)) {
@@ -120,8 +120,11 @@ namespace ts {
         return undefined;
     }
 
-    /** Like `forEach`, but assumes existence of array and fails if no truthy value is found. */
-    export function find<T, U>(array: T[], callback: (element: T, index: number) => U | undefined): U {
+    /**
+     * Returns the first truthy result of `callback`, or else fails.
+     * This is like `forEach`, but never returns undefined.
+     */
+    export function findMap<T, U>(array: T[], callback: (element: T, index: number) => U | undefined): U {
         for (let i = 0, len = array.length; i < len; i++) {
             const result = callback(array[i], i);
             if (result) {
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 0598c34bd7bff..8b32d5351eaf8 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2715,7 +2715,7 @@ namespace ts {
 
     /** Return ".ts" or ".tsx" if that is the extension. */
     export function tryExtractTypeScriptExtension(fileName: string): string | undefined {
-        return tryFind(supportedTypescriptExtensionsWithDtsFirst, extension => fileExtensionIs(fileName, extension));
+        return find(supportedTypescriptExtensionsWithDtsFirst, extension => fileExtensionIs(fileName, extension));
     }
     // Must have '.d.ts' first because if '.ts' goes first, that will be detected as the extension instead of '.d.ts'.
     const supportedTypescriptExtensionsWithDtsFirst = supportedTypeScriptExtensions.slice().reverse();

From 8fc17afa003d53aa7baf914883f2b20606e8a879 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Thu, 18 Aug 2016 14:11:30 -0700
Subject: [PATCH 6/7] Move supportedTypescriptExtensionsWithDtsFirst next to
 supportedTypeScriptExtensions and rename

---
 src/compiler/core.ts      | 2 ++
 src/compiler/utilities.ts | 6 ++----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index d2ea69b304dd7..808f8a538df64 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1243,6 +1243,8 @@ namespace ts {
      *  List of supported extensions in order of file resolution precedence.
      */
     export const supportedTypeScriptExtensions = [".ts", ".tsx", ".d.ts"];
+    /** Must have ".d.ts" first because if ".ts" goes first, that will be detected as the extension instead of ".d.ts". */
+    export const supportedTypescriptExtensionsForExtractExtension = [".d.ts", ".ts", ".tsx"];
     export const supportedJavascriptExtensions = [".js", ".jsx"];
     const allSupportedExtensions  = supportedTypeScriptExtensions.concat(supportedJavascriptExtensions);
 
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 8b32d5351eaf8..faf210e461fd8 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2713,12 +2713,10 @@ namespace ts {
         return forEach(supportedTypeScriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
 
-    /** Return ".ts" or ".tsx" if that is the extension. */
+    /** Return ".ts", ".d.ts", or ".tsx", if that is the extension. */
     export function tryExtractTypeScriptExtension(fileName: string): string | undefined {
-        return find(supportedTypescriptExtensionsWithDtsFirst, extension => fileExtensionIs(fileName, extension));
+        return find(supportedTypescriptExtensionsForExtractExtension, extension => fileExtensionIs(fileName, extension));
     }
-    // Must have '.d.ts' first because if '.ts' goes first, that will be detected as the extension instead of '.d.ts'.
-    const supportedTypescriptExtensionsWithDtsFirst = supportedTypeScriptExtensions.slice().reverse();
 
     /**
      * Replace each instance of non-ascii characters by one, two, three, or four escape sequences

From b452469419cfed00dc5b04f4d286c2c700ef2619 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Fri, 19 Aug 2016 06:14:28 -0700
Subject: [PATCH 7/7] Fix tests

---
 tests/baselines/reference/exportDefaultProperty2.js      | 6 +++---
 tests/baselines/reference/exportDefaultProperty2.symbols | 2 +-
 tests/baselines/reference/exportDefaultProperty2.types   | 2 +-
 tests/baselines/reference/exportEqualsProperty2.js       | 4 ++--
 tests/baselines/reference/exportEqualsProperty2.symbols  | 2 +-
 tests/baselines/reference/exportEqualsProperty2.types    | 2 +-
 tests/cases/compiler/exportDefaultProperty2.ts           | 2 +-
 tests/cases/compiler/exportEqualsProperty2.ts            | 2 +-
 8 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/tests/baselines/reference/exportDefaultProperty2.js b/tests/baselines/reference/exportDefaultProperty2.js
index 88f0fbb4e20f9..2b0a5dce526d7 100644
--- a/tests/baselines/reference/exportDefaultProperty2.js
+++ b/tests/baselines/reference/exportDefaultProperty2.js
@@ -13,7 +13,7 @@ namespace C {
 export default C.B;
 
 //// [b.ts]
-import B from "./a.ts";
+import B from "./a";
 const x: B = { c: B };
 
 
@@ -29,5 +29,5 @@ exports.__esModule = true;
 exports["default"] = C.B;
 //// [b.js]
 "use strict";
-var a_ts_1 = require("./a.ts");
-var x = { c: a_ts_1["default"] };
+var a_1 = require("./a");
+var x = { c: a_1["default"] };
diff --git a/tests/baselines/reference/exportDefaultProperty2.symbols b/tests/baselines/reference/exportDefaultProperty2.symbols
index 7ac99d53a0898..d3d7519aa94ef 100644
--- a/tests/baselines/reference/exportDefaultProperty2.symbols
+++ b/tests/baselines/reference/exportDefaultProperty2.symbols
@@ -21,7 +21,7 @@ export default C.B;
 >B : Symbol(default, Decl(a.ts, 2, 9), Decl(a.ts, 5, 13))
 
 === tests/cases/compiler/b.ts ===
-import B from "./a.ts";
+import B from "./a";
 >B : Symbol(B, Decl(b.ts, 0, 6))
 
 const x: B = { c: B };
diff --git a/tests/baselines/reference/exportDefaultProperty2.types b/tests/baselines/reference/exportDefaultProperty2.types
index 8dff23f1c8916..2fc9d3a475057 100644
--- a/tests/baselines/reference/exportDefaultProperty2.types
+++ b/tests/baselines/reference/exportDefaultProperty2.types
@@ -21,7 +21,7 @@ export default C.B;
 >B : number
 
 === tests/cases/compiler/b.ts ===
-import B from "./a.ts";
+import B from "./a";
 >B : number
 
 const x: B = { c: B };
diff --git a/tests/baselines/reference/exportEqualsProperty2.js b/tests/baselines/reference/exportEqualsProperty2.js
index 283fa3996a75a..b5d91431722e3 100644
--- a/tests/baselines/reference/exportEqualsProperty2.js
+++ b/tests/baselines/reference/exportEqualsProperty2.js
@@ -13,7 +13,7 @@ namespace C {
 export = C.B;
 
 //// [b.ts]
-import B = require("./a.ts");
+import B = require("./a");
 const x: B = { c: B };
 
 
@@ -28,5 +28,5 @@ var C = (function () {
 module.exports = C.B;
 //// [b.js]
 "use strict";
-var B = require("./a.ts");
+var B = require("./a");
 var x = { c: B };
diff --git a/tests/baselines/reference/exportEqualsProperty2.symbols b/tests/baselines/reference/exportEqualsProperty2.symbols
index a765e95bdf39a..df7eda76661cf 100644
--- a/tests/baselines/reference/exportEqualsProperty2.symbols
+++ b/tests/baselines/reference/exportEqualsProperty2.symbols
@@ -1,5 +1,5 @@
 === tests/cases/compiler/b.ts ===
-import B = require("./a.ts");
+import B = require("./a");
 >B : Symbol(B, Decl(b.ts, 0, 0))
 
 const x: B = { c: B };
diff --git a/tests/baselines/reference/exportEqualsProperty2.types b/tests/baselines/reference/exportEqualsProperty2.types
index 90b239e7bb6ed..4594cbfd01541 100644
--- a/tests/baselines/reference/exportEqualsProperty2.types
+++ b/tests/baselines/reference/exportEqualsProperty2.types
@@ -1,5 +1,5 @@
 === tests/cases/compiler/b.ts ===
-import B = require("./a.ts");
+import B = require("./a");
 >B : number
 
 const x: B = { c: B };
diff --git a/tests/cases/compiler/exportDefaultProperty2.ts b/tests/cases/compiler/exportDefaultProperty2.ts
index 180a58a22d49c..0db617c93e1ee 100644
--- a/tests/cases/compiler/exportDefaultProperty2.ts
+++ b/tests/cases/compiler/exportDefaultProperty2.ts
@@ -11,5 +11,5 @@ namespace C {
 export default C.B;
 
 // @Filename: b.ts
-import B from "./a.ts";
+import B from "./a";
 const x: B = { c: B };
diff --git a/tests/cases/compiler/exportEqualsProperty2.ts b/tests/cases/compiler/exportEqualsProperty2.ts
index 6a07837334a21..61f117f162938 100644
--- a/tests/cases/compiler/exportEqualsProperty2.ts
+++ b/tests/cases/compiler/exportEqualsProperty2.ts
@@ -11,5 +11,5 @@ namespace C {
 export = C.B;
 
 // @Filename: b.ts
-import B = require("./a.ts");
+import B = require("./a");
 const x: B = { c: B };